The treatment improved pain and function, and in up to 73% of patients, appeared to delay the progression of osteoarthritis, which is a progressive disease. The study appears online, ahead of print, in the Clinical Journal of Sports Medicine.

Several treatments for osteoarthritis exist, including exercise, weight control, bracing, nonsteroidal anti-inflammatories, Tylenol, cortisone shots and viscosupplementation, a procedure that involves injecting a gel-like substance into the knee to supplement the natural lubricant in the joint. A new treatment that is being studied by a small number of doctors is PRP injections. PRP, which is produced from a patient’s own blood, delivers a high concentration of growth factors to arthritic cartilage that can potentially enhance healing.

“You take a person’s blood, you spin it down, you concentrate the platelets, and you inject a person’s knee with their own platelets in a concentrated form,” said Dr. Halpern. “This then activates growth factors and stem cells to help repair the tissue, if possible, calm osteoarthritic symptoms and decrease inflammation.”

In the new study, researchers at Hospital for Special Surgery enrolled patients with early osteoarthritis, gave them each an injection of PRP (6-mL), and then monitored them for one year. Fifteen patients underwent clinical assessments at baseline, one week, and one, three, six, and 12 months. At these time points, clinicians used validated tools to assess overall knee pain, stiffness and function, as well as a patient’s ability to perform various activities of daily living. At baseline and then one year after the PRP injection, physicians also evaluated the knee cartilage with magnetic resonance imaging (MRI), something that has not previously been done by researchers in other PRP studies. The radiologists reading the MRIs did not know whether the examination was performed before or after the PRP treatment.

“The problem with a lot of the PRP studies is that most people have just used subjective outcome instruments, such as pain and function scores,” said Hollis Potter, M.D., chief of the Division of Magnetic Resonance Imaging at Hospital for Special Surgery, another author of the study. “But even when patients are blinded, they know there has been some treatment, so there is often some bias interjected into those types of studies. When you add MRI assessment, it shows you the status of the disease at that time, regardless of whether the patient is symptomatic or asymptomatic or they have good or poor function in the knee. You find out what the cartilage actually looks like. We can noninvasively assess the matrix or the building blocks of cartilage.”

While previous studies have shown that patients with osteoarthritis can lose roughly five percent of knee cartilage per year, the HSS investigators found that a large majority of patients in their study had no further cartilage loss. “The knee can be divided into three compartments, the medial compartment, the lateral compartment and the patellofemoral compartment,” said Dr. Halpern. “If we look at these compartments individually, which we did, in at least 73% of these cases, there was no progression of arthritis per compartment at one year. That is very significant, because longitudinal studies suggest a four to six percent progression of arthritis at one year.”